Pocket-ammeter.



No. 839,637. PATENTED DEC. 25, 1906. H. POEHN & M. JURUIGK.

POCKET AMMETBR.

APPLICATION FILED 1130.1, 1905.

m mvm W 2 Law fi w WITNESSES: ci a UNITED srArEs PATENT. OFFICE.

HERMANN POEHN, OFJERSEY CITY, NEW JERSEY, AND MAXIMILI'AN JURUICK, OFNEW YORK, N. Y.

POCKET-AMMETER.

Specification of Letters Patent.

Patented Dec. 25, 1906.

Application filed December 1, 1906. Seria1No. 289,749.

To all whom it may concern -Be it known that we, HERMANN Forum, aresident of J erse City, in the county of Hudson.and State 0 New Jersey,and MAXIMIL- IAN JURUICK, a resident of New York, in the county andStateof New York, citizens of. the United States, have ointly inventedcertain new and useful Improvements in Pocket- Ammeters, of which thefollowing is a specification.

This invention has reference to improvements in pocket-ammeters, andpertains particularly to -that kind of ampere-meters known as thewatchcase type.

The novel ammeter is a direct-readin instrument. Its scale usuallyranges rom zero to thirty or forty or fifty amperes or any othersuitable number. i

It is thespecial object of this invention to provide a pocket-ammeterwith a peculiarlyshaped armature located between the poles of anelectromagnet of nearly-circular form. The weight or the mass of thematerial of the armature is so arranged that the inner portion of sameis heaviest, while the ends are narrow and light.

The novel ammeter, further, is provided with a loose rin for theadjustment of the starting-point o the armature or its normal positionin relation to the poles of the electromagnet. This is not done,directly, but by means of the hair-spring generally employed in suchinstruments and by a pinion and gearwheel, as will be fully explainedfarther down.

The invention is illustrated in the accompanying drawings, in which-Figure 1 represents in top plan view a pocket-ammeter which embodies ourinvention. Fig. 2 illustrates same in top plan view with dial andpointer removed. Fig. 3 is a rear view of the instrument with the rearcover removed. Fig. 4 is a detail view of the essential operativemechanism, and Fig. 5 is a plan view of Fig. 4.

Similar characters of reference denote like parts in all the figures.

In the drawings, a represents the casing, which is cut out in the rear,as shown in Fig. 3. At the bottom an opening I) is cut into the casingto allow of passing through one end of the contact 0. Just opposite thisopenin there is the knob d, which is hollowed out an provided with ascrew-thread on the inside 'h. (See Fig. 2.)

for the purpose of receiving one end of the second contact 0.

Within the casing there is mounted a brass disk e, which has a centralopening and. a tongue .2. The ton ue extends inwardly to the center ofthe dis of nearly-circular shape is secured on the dis by means ofscrews. The core f 2 of the magnet consists of soft iron, which retainspracticall noresidu'al magnetism when no current ows through same. Thepoles f of the ma net are turned inwardly, as shown in Fig. 4. he magnethas two windings of wire. The two ends ww, one of each winding, aresoldered to the metal diske, while the two other ends w w are solderedto a small piece of metal g, which is provided with a threaded openingfor receivin the one end of the contact 0 that has a threa on theoutside. A ring of insulating material 0 is secured to the contact 0.Within the casing there is a curved piece of insulating material 0 whichhas 'a circular opening for the passage of the contact 0. The ring 0 andthe piece a insulate the contacts from the casing, which forms part ofthe circuit of the magnet-wire. The current passes from the contact 0through the electroma net, the casing, the knob d, and out throug thecontact 0.

Upon the disk e there is mounted a bridge The bridge is secured 1n thecenter of the disk and extends u wardly into'a branch h. It carries twosma 1 shafts i j, which rest in the disk e, each on a hardened plate toinsure of easy movement; but

this is not shown on the drawin s. The shaft,

i rests on the tongue e of the dis e and passes through the brid e h anddial is. A pointer is is attached to the top end of this shaft. A smallpinion Z is mounted on the shaft '5 right below the bridge and ahair-spring 8 below the pinion. The shaft 7' carries a'gear-wheel m andbelow same the armature 'n, which is in one horizontal plane with thepoles of the electromagnet. The bottom surface of the An electromagnet gdisk carries a-loose ring 0, which is surrounded by a supporting-ring 0.The ring 0 has a rectangular arm 0 extending upward. The outer end ofthe hair-spring is secured to this arm, while the inner end of same isfastened to a small hub on the shaft 'i.

The armature n also is made of soft iron, which quickly demagnetizes.

10 5 It is of pecul- 7 pointed at the two ends and increases 111widthtoward the center cross-bar n, which is broadest. In this Waytheweight of the armature is so distributed that the pointed ends, whichare normally near the oles of the electromagnet, are very light, w 'Iethe center cross-bar is relativelyheavy. When current flows through theelectr'omagnet, then the distance between the heavy bar of the armatureand the poles of the electro- -'mag'net decreases, becausethe armatureis turned in accordance with the strength of the -'em'rent flowingthrough the instrument.

Asabeve stated, the wire spring s has-one endattached to'the rectangulararm 0 of the loosering 0, while the inner-end is secured to the smal hubon the pinion andspring shaft 11-. By turningthe loose ring thestarting- -pointor the osition of the armature ends in relation to "t epoles of the electromagnet may be adjusted. This is another feature ofthis invention. It is plainly understood that the ointer k", which issecured to the top end of 't e pinion ands ring shaft, will move whenthe spring is a ected by the armature, which moves the gear and pinionwhen current flows throughthe instrument.

Having thus described our invention, we claim as new and desireto secureby Letters Patent 1. A ocket-ammeter comprising a casing, a meta diskmounted therein, an electromagnet secured to said disk, an S-shapedarmature mounted on a movable shaft between the poles of theelectromagnet, a gear-wheel -on said shaftabove the armature, a pinionsecond shaft in the center-ofthe instrument,

a ointer on the top end of the pinion-shaft, a 'al below the polnter, ahair-spring on the pinion-shaft below the pinion, and a loose ring onthe bottom surface ofthe-disk having ,a rectangular arm to which one endof the hair-spring is secured whereby the position of the armature endsmay be adjusted in'relation to the poles of the electromagnet.

'3. In a pocket-ammeter an electromagnet of nearly-circular form andhaying turned-in poles, an 'S-shaped armature'mounted 'between saidpoles and in one plane with same on a movable shaft, a gear-wheel onsaid shaft above the armature, a pinion mounted on a second shaft, ahair-spring on thepinionshaft below said pinion, and a loose ring havinga rectan lar arm to which one end ofthe hair-spring 1s secured wherebythe position of the armature ends may be adjusted in relation to thepoles of the electromagne't.

In testimony whereof we have hereunto set our hands, this 29th day ofNovember, 1905, in the presence of two subscribing witnesses.

' HERMANN 'POEHN. MAX. JURUICK,

Witnesses:

LUDWIG K- Berna, JAMES J. ASTARITA.

